The FamilySearch Wiki article Glossary of United States Probate Terms says:
Relinquishment - Relinquishment is to waive one's rights.
To see an overview of how the law has changed over time, see the article What are dower rights?. To find out exactly what law was in force at the time, you would want to look up the relevant section of the state statutes.
Typically the widow would be required to sign a document saying she was giving up her right in her husband's estate before real property (land) could be sold. You don't say whether you found a probate packet (loose papers) or probate records in court record books -- whichever one you have, try to find the others, especially the court docket books.
This is an example of a court docket book from my research in Massachusetts, indexing documents from various stages in the case as the estate went through probate. All of the references refer to the appropriate volumes and pages in the bound court records, and the will is from a copybook. (There should also be a packet of loose probate papers with the same case number, but I haven't found it yet -- probate packets for this court may not be online yet.)
Follow the land records, and see if you can find a quitclaim deed where the widow gives up her rights to her husband's property. You'll want to look in the court records for the county where the land is located. See the FamilySearch Wiki article Ohio Land and Property and the Wiki article for the specific county for more information.
Historical newspapers can be valuable, especially the sections containing legal notices. To see what newspapers may have been published in the area, use the US Newspaper Directory at the Library of Congress' Chronicling America, which will tell you what titles and issues survive and are held in libraries. If the online collection of newspapers at Chronicling America doesn't have the newspapers you need, you can use these resources to find other newspapers online before you go to the library:
There has been record loss in some areas of Ohio -- for strategies on getting around that, see the article on Burned Counties research. Newspapers can be especially helpful when the original court records have been lost.
To make a wider search for records which might contain the widow's name, look for Christina K Schaefer's book The Hidden Half of the Family, which has timelines for each US State describing changes in laws. Use WorldCat to find it in a library near you, preview it on Google Books, or see the publisher's website for more details. The book is available in print, and as an ebook (viewable online, in Mobi format (Kindle), and as an ePub). The publisher's description says, in part:
Each state section begins with a time line of events, i.e. important
dates in the state's history, following which is a detailed listing of
eight key categories of information: (1) Marriage and Divorce
(marriage and divorce laws and where to find marriage and divorce
records; (2) Property and Inheritance (women's legal status in a state
as reflected in statute law, code, and legislative acts); (3) Suffrage
(information as to when any voting rights were granted prior to the
ratification of the 19th Amendment in 1920); (4) Citizenship (dates
when residents of an area became U.S. citizens); (5) Census
Information (special notes on searching federal, state, and
territorial enumerations); (6) Other (information on welfare,
pensions, and other laws affecting women); (7) Bibliography (books and
articles relating to women in the state, historical and biographical
sources, and publications regarding legal history and jurisprudence);
and (8) Selected Resources for Women's History (addresses of state
archives, historical societies, and libraries; women's studies
programs, women's history programs, and more).
Even with the help of a work like Schaefer's, you may not be able to find a single document that will state the identity of the widow. In that case, you may need to build a case using indirect evidence. Look for articles in genealogy publications from people working in the same area, and see what sources they were able to find, and see how they used them to build their case.